Tissues — Science Class 9 Notes (CBSE & HBSE)
Free NCERT Science notes for Tissues (Class 9) on Siksha Sarovar, aligned to CBSE and Haryana Board (HBSE). This chapter is broken into 3 topics with clear explanations, formulas, solved examples and board-pattern practice — free to read, no sign-up required.
Board exam focus — Tissues (CBSE & HBSE)
CBSE emphasises classification with structure-function correlation and labelled-diagram-based reasoning for plant (meristematic/permanent) and animal tissues. HBSE focuses on definitions, location and differences (e.g. parenchyma vs sclerenchyma, xylem vs phloem, types of muscles) as short-answer recall.
Plant Tissues: Meristematic and Permanent (Simple & Complex)
What is a Tissue?
A tissue is a group of cells similar in structure and origin that work together to perform a specific function. Multicellular organisms show division of labour through tissues.
Meristematic Tissue
Meristematic tissue consists of actively dividing cells found in growing regions. Its cells are small, thin-walled, with dense cytoplasm, prominent nuclei and no vacuoles.
| Type | Location | Function |
|---|---|---|
| Apical meristem | Tips of roots and shoots | Increase in length (primary growth) |
| Lateral meristem (cambium) | Sides (girth region) | Increase in girth/thickness |
| Intercalary meristem | At the base of leaves or internodes | Increase in length |
Permanent Tissue
Cells formed by meristematic tissue lose the ability to divide and take a permanent shape, size and function \u2014 this is differentiation. Permanent tissue is of two types: simple and complex.
Simple Permanent Tissues
| Tissue | Features | Function |
|---|---|---|
| Parenchyma | Living, thin-walled, with intercellular spaces | Storage, support; chlorenchyma (with chloroplast) does photosynthesis; aerenchyma (air cavities) gives buoyancy to aquatic plants |
| Collenchyma | Living, irregularly thickened at corners | Flexibility and mechanical support (e.g. in leaf stalks) |
| Sclerenchyma | Dead, very thick lignified walls, no intercellular space | Provides hardness and rigidity (e.g. husk of coconut, stem) |
Trap: Sclerenchyma cells are dead at maturity and have lignin deposited in their walls; parenchyma and collenchyma are living. Aerenchyma and chlorenchyma are types of parenchyma.
Protective Tissue
- Epidermis: outer protective layer; often coated with a waxy cutin that prevents water loss. Stomata (with guard cells) in the epidermis allow gas exchange and transpiration.
- Cork (bark): dead cells with suberin in walls, making them impervious to gases and water.
Complex Permanent Tissues
Complex tissues are made of more than one type of cell and are conducting tissues.
| Tissue | Components | Function |
|---|---|---|
| Xylem | Tracheids, vessels, xylem parenchyma, xylem fibres | Conducts water and minerals upward from roots to leaves; gives support |
| Phloem | Sieve tubes, companion cells, phloem parenchyma, phloem fibres | Transports food from leaves to other parts (translocation) |
Trap: Most xylem components (tracheids, vessels, fibres) are dead; only xylem parenchyma is living. In phloem, all are living except phloem fibres.
Animal Tissues: Epithelial and Connective Tissue
Epithelial Tissue
Epithelial tissue is the covering or protective tissue that lines the body surfaces, cavities and organs. Cells are tightly packed with little intercellular space, resting on a basement membrane.
| Type | Structure | Location/Function |
|---|---|---|
| Squamous | Flat, thin cells | Lining of mouth, blood vessels, alveoli; protection and diffusion |
| Stratified squamous | Many layers of flat cells | Skin; prevents wear and tear |
| Cuboidal | Cube-like cells | Lining of kidney tubules, ducts; absorption and secretion |
| Columnar | Tall pillar-like cells | Lining of intestine; absorption and secretion |
| Ciliated columnar | Columnar cells with cilia | Lining of respiratory tract; moves mucus/particles |
| Glandular | Folded epithelium forming glands | Secretion of enzymes, hormones, sweat |
Connective Tissue
Connective tissue connects, supports, binds and packs together different organs. Its cells are loosely spaced in an intercellular matrix.
| Connective Tissue | Matrix/Features | Function |
|---|---|---|
| Blood | Fluid matrix (plasma) with RBCs, WBCs, platelets | Transport of gases, nutrients, wastes, hormones |
| Bone | Hard matrix of calcium and phosphorus | Framework, support and protection of body |
| Cartilage | Solid yet flexible matrix | Smoothens bone surfaces at joints; present in nose, ear, trachea |
| Ligament | Very elastic, strong fibres | Connects bone to bone |
| Tendon | Fibrous, great strength, limited flexibility | Connects muscle to bone |
| Areolar | Loose tissue, fills spaces | Fills space between organs, supports internal organs, repairs tissues |
| Adipose | Fat-storing cells | Stores fat; acts as insulator |
Trap: Blood is a connective tissue because it has a (fluid) matrix and connects body parts by transport. Ligament connects bone to bone; tendon connects muscle to bone \u2014 do not swap these.
Animal Tissues: Muscular and Nervous Tissue
Muscular Tissue
Muscular tissue consists of elongated cells called muscle fibres that contract and relax to cause movement. There are three types:
| Muscle Type | Other Name | Striations | Control | Location |
|---|---|---|---|---|
| Striated | Skeletal / voluntary | Present (striped) | Voluntary | Attached to bones; limbs |
| Smooth | Unstriated / involuntary | Absent | Involuntary | Walls of stomach, intestine, blood vessels |
| Cardiac | Heart muscle | Present (faint) | Involuntary | Walls of the heart |
Key points:
- Striated muscles are cylindrical, multinucleate and unbranched; under our control.
- Smooth muscles are spindle-shaped, uninucleate; work without our will (e.g. movement of food in the alimentary canal).
- Cardiac muscles are branched, uninucleate, striated and rhythmically contract and relax throughout life without fatigue.
Trap: Cardiac muscle is striated but involuntary \u2014 it shows features of both striated and smooth muscle, which is a common exam confusion.
Nervous Tissue
Nervous tissue is highly specialised for being stimulated and conducting impulses rapidly. The brain, spinal cord and nerves are all made of nervous tissue.
The functional unit of nervous tissue is the neuron (nerve cell). A neuron has:
- Cell body (cyton): contains the nucleus and cytoplasm.
- Dendrites: short branched projections that receive impulses.
- Axon: a single long fibre that carries the impulse away from the cell body.
A single neuron can be up to a metre long. Nerve impulses allow animals to respond quickly to stimuli; the combination of nerve and muscle tissue is fundamental to most animals.
Tip: Remember the impulse path \u2014 dendrite \u2192 cell body \u2192 axon \u2192 next neuron/muscle.
Frequently asked questions
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Do these notes follow CBSE and HBSE?
Yes. The Tissues notes are NCERT-aligned and include guidance for both CBSE and Haryana Board (HBSE), with important questions and MCQs for revision.
What does the Tissues chapter cover?
Concept explanations, key formulas and definitions, fully solved examples and board-pattern practice questions for Tissues.